1. Field of the Invention
Embodiments described herein generally relate to an apparatus and method of protecting one or more optical fibers. More particularly, the apparatus includes an optical fiber having a portion which is covered by an elastomeric material. More particularly still, the elastomeric material is configured to prevent erosion of the optical fibers in a wellbore.
2. Description of the Related Art
In the drilling of oil and gas wells, a wellbore is formed using a drill bit that is urged downwardly at a lower end of a drill string. After drilling a predetermined depth, the drill string and bit are removed and the wellbore is lined with a string of casing. An annular area is thus formed between the string of casing and the wellbore. A cementing operation is then conducted in order to fill the annular area with cement. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.
The wellbore may be produced by perforating the casing of the wellbore proximate a production zone in the wellbore. Hydrocarbons migrate from the production zone, through the perforations, and into the cased wellbore. In some instances, a lower portion of a wellbore is left open, that is, it is not lined with casing. This is known as an open hole completion. In that instance, hydrocarbons in an adjacent formation migrate directly into the wellbore where they are subsequently raised to the surface, possibly through an artificial lift system.
During the production of the zone, sand and other aggregate and fine materials may be included in the hydrocarbon that enters the wellbore. These aggregate materials present various risks concerning the integrity of the wellbore. Sand production can result in premature failure of artificial lift and other downhole and surface equipment. Sand can build up in the casing and tubing to obstruct well flow. Particles can compact and erode surrounding formations to cause liner and casing failures. In addition, produced sand becomes difficult to handle and dispose of at the surface.
To control particle flow from production zones, sand screens are often employed downhole proximate the production zone. The sand screens filter sand and other unwanted particles from entering the production tubing. The sand screen is connected to production tubing at an upper end and the hydrocarbons travel to the surface of the well via the tubing.
In well completions, the operator oftentimes wishes to employ downhole tools or instruments in the wellbore. These include sliding sleeves, submersible electrical pumps, downhole chokes, and various sensing devices. These devices are controlled from the surface via hydraulic control lines, electrical control lines, mechanical control lines, fiber optics, and/or a combination thereof. For example, the operator may wish to place a series of pressure and/or temperature sensors every ten meters within a portion of the hole, connected by a fiber optic control line. This line would extend into that portion of the wellbore where a sand screen or other tool has been placed.
In order to protect the control lines or instrumentation lines, the lines are typically placed into small metal tubings which are affixed external to the tubular and the production tubing within the wellbore. The metal tubing is rapidly eroded when placed in a flow path containing sand or other aggregate materials. The erosion of the metal tubing causes the eventual failure of the control line or instrument line. The replacement of the control line is expensive and may delay other production or work on the drill rig.
There is a need for a control or instrument line for use in a wellbore having an abrasive resistant material on an outer surface. There is a further need for a line having an elastomeric material on its outer surface. There is a further need for the elastomeric material to be located only in a zone that is exposed to highly abrasive flow.